HEXACTINELLA MONTICULARIS. 147 
disc, 1-2.5 » in transverse diameter (Plate 28, figs. 11, 20). Sometimes these 
spines are so small that the end-rays appear terminally rounded and destitute 
of terminal discs. 
The scopules (Plate 28, figs. 1-9, 13, 14) are 220-400 » long. They consist, 
of a stout centrum, from one side of which arises a simple shaft, and from the 
opposite a verticil of end-rays. Sometimes one or two end-rays are also attached 
to the sides of the centrum. 
The centrum is 6.2-9.6 » broad, 4-9 » long, and has four lateral protuber- 
ances arranged regularly crossways. When small these protuberances appear 
as slight rounded elevations (Plate 28, figs. 7-9), when large as short, cylindrical, 
terminally rounded ray-rudiments, equaling the shaft in thickness (Plate 28, 
figs. 5, 6). The centrum and its protuberances are uniformly and densely 
covered with minute spines. 
The shaft is 200-345 yw long, straight or, rarely, curved. It is nearly 
cylindrical for the greater part of its length, and rather abruptly attenuated to a 
sharp point. It is 3-4.5 » thick at the base, where it rises from the centrum; 
in the middle of its length it is slightly thinner, or, not so frequently, as thick or 
slightly thicker than basally. The middle-part of the shaft is nearly smooth. 
The proximal part, for a distance of about 30 » from the centrum, is, like the 
centrum, densely covered with minute spines. Ina belt which is 10-20 » broad 
and situated a short distance from the distal end, larger, particularly broader 
sparsely scattered spines occur. 
Of end-rays there are from five to nine, most frequently seven. As men- 
tioned above, these generally all rise from the apex of the centrum, that is the 
face opposite the shaft. These terminal end-rays are slightly curved, concave 
to the continuation of the axis of the shaft for a short distance, and, for the 
remainder of their length, straight or curved slightly in the opposite direction 
(outwards). They diverge above more or less and together form a stouter or 
more slender, brush-like or calyculate verticil, 9-22 » broad at the distal end. 
These end-rays are 11-65 » long, most frequently 11-30 ». Of 33 measured: — 
0 was under 10 wu long. 1 was 36-40 » long 
5 were 11-15 u a Om SS Ale 
9 “ 16-20 u nS 1 “ 46-50 4 “ 
CO 2S 2bin S Ones tol-a5) 7 
he 51 226-30) OM 856-60 Ge 
2 31-35 in e eer s61=65ij0 
0 was over 66 » long 
